Indian scientists develop biodegradable, edible coating for fresh produce to boost shelf life

07 Sep 2022 --- Biodegradable, antioxidant-rich edible active films and coatings from micro-algae extract that extend shelf life can offer fresh produce a new lease of life, following research from the Indian Institute of Technology (IIT) Guwahati. 

Offering two months food preservation extension, the coatings don’t interfere with taste or quality and also mitigate environmental hazards caused by non-biodegradable food-packaging waste. This coating will reduce food loss along the production and supply chain.

Speaking to FoodIngredientsFirst, Prof. Vimal Katiyar of IIT’s department of chemical engineering and center for excellence in sustainable polymers (CoE-SusPol), dives into the process. 

“The formulated algae extract incorporated edible coating exhibited delayed germination/budding in coated [vegetables] as compared to uncoated,” he explains. 

“This developed coating will help farmers protect their harvest and reduce the post-harvest loss.”

He explains the problem with cold storage facilities is availability and the price to borrow. Using the cost-effective edible coating developed by the researchers, farmers can extend the shelf life, thus minimizing loss of produce and economy.

“According to the Indian Council of Agricultural Research, between 4.6-15.9% of fruits and vegetables go waste post-harvest, partly due to poor storage conditions,” Prof. Katiyar continues. 

“Post-harvest loss in certain produce items like potato, onion and tomato could be as high as 19%, which results in high prices for this highly consumed commodity.”

Mitigating post-harvest losses could be particularly poignant at this time of inflation, rising food baskets and increased energy costs. 

The developed coating will help farmers protect their harvest as well as reduce the post-harvest loss.“First development”
The study aimed to upcycle the biowaste de-oiled green algae biomass (DAB) of Dunaliella tertiolecta – a model marine algae – using a green approach. 

Ultrasound-assisted green extraction was conducted using food-grade solvent ethanol for obtaining the bio-actives, namely “crude algae ethanolic extract (CAEE)” from DAB to develop biodegradable chitosan (CS)-based edible active biocomposite films and coatings.

The addition of CAEE into the CS matrix reduced the maximum film transparency (20%), water vapor permeability (60%) and improved crystallinity (24%), tensile strength (25%) and antioxidant activity (27%). Additionally, it exhibited UV-Vis blocking properties as compared to the control film.

The developed coating solutions and CAEE showed antimicrobial activity against common food pathogens.

Food packaging solution
The fabricated CAEE-incorporated CS-based biocomposite films contain amino and hydroxyl groups in the CS chain, which play a significant role in developing edible coating via hydrogen, covalent and amide bonding. 

The study found CAEE to be rich in antioxidants with radical-scavenging activity. Further, CAEE contains an adequate number of bioactive molecules of polyphenols, such as carotenoids, proteins, polysaccharides and sugars.

The coating also displayed a superior total phenolic content, water vapor barrier property, thermal stability and mechanical strength.

These CS-based edible active biocomposites are incorporated with CAEE as a biofiller as a secondary packaging material and application of a formulated filmogenic solution as a coating material on a natural food system.

The developed formulation for edible coating can be applied on other fresh produce such as tomato, potato, onion and chili, among others, using a dipping technique for primary or secondary coating.

By Radhika Sikaria